Personal care absorbent products abound in the market place. Such products are used by persons of all ages and include diapers, training pants, adult incontinence articles and feminine hygiene products such as tampons and sanitary napkins. Personal care absorbent products are often subjected to efficacy testing during the product development phase as well as to substantiate advertising claims directed to the commercialized product.
Efficacy testing may be completed in vivo and/or in vitro. In vivo tests may require panelists to wear a product for a finite time, and then return the used product for data collection and evaluation. In vivo testing can be costly and time-consuming. Moreover, in vivo testing exposes the data collector to the potential risk of contact with bodily fluids and associated pathogens. In vitro testing can offer a higher degree of experimental control and precision than in vivo testing. For these reasons, in vivo test procedures and artificial body exudates have been developed for in vitro testing. For instance, the developers of feminine hygiene products have liquid substitutes for menstrual fluid that are used in laboratory testing and efficacy demonstrations.
Fluid properties such as surface tension, viscosity, stringiness, and the size and concentration of particulate matter may affect the interaction of any fluid with the porous surfaces and absorbent materials that form today's highly engineered, high performance feminine hygiene products. Many of the conventional artificial menstrual fluids do not emulate all of these properties. For example, some artificial fluids are liquid solutions with all of the solids dissolved therein. Artificial fluids that lack solids tend to be absorbed more readily than real menstrual fluid, which is a multi-phase suspension of particulate matter in an aqueous liquid. Some artificial fluids do not contain blood despite observations that real menstrual fluid has properties similar to blood particularly during periods of high flow. Other artificial fluids currently in use do not contain mucus or other ingredients necessary to impart the type of stringy viscoelastic behavior typical of real menstrual fluid.
In order for in vitro testing of absorbent feminine hygiene products to provide data that are most directly comparable with in vivo data, the menstrual fluid simulant should closely emulate the physical properties of real menstrual fluid. Therefore, a menstrual fluid simulant that comprises the properties of real menstrual fluid is desirable.
The fluid properties of real menstrual fluid are highly variable from woman to woman and may even vary with regard to an individual woman over the course of her menstrual period. Therefore, a menstrual fluid simulant with a composition that can be adjusted to emulate variations in the properties of real menstrual fluid is also desirable.